Hide empty modules for smart content in drag and drop editor

[ClaraS]

 Would be great to be able to hide variations that does not have any content in them. For example, when contacts in one list should only see 3 content modules, and contacts in another list should see 5 content modules in a newsletter. Today it's possible to leave it empty, but it will create awkward spacing. 

[AlexBril]

This idea adds real value to smart rules in marketing emails